1. Field of the Invention
The present invention relates to cutting tools, namely inserts for machine tools, and more particularly, to small size inserts for grooving and turning.
2. Description of Related Art
The art of cutting grooves in a workpiece using a cutting tool, and particularly using an insert secured in a toolholder is well known. The use of an insert in a toolholder for turning, i.e., removing portions of material from a rotating workpiece by causing the insert to traverse along a portion of the longitudinal surface of the workpiece while the insert is sequentially advanced into the surface of the workpiece, is also known.
In one method of securing the insert during its use, particularly for grooving, cutting or threading, the insert is clamped adjacent one side of a toolholder. In this arrangement the toolholder has a nest or pocket formed by a bottom wall and a side wall, and the insert is held in position by a top clamp. Such an arrangement is illustrated in U.S. Pat. No. 3,754,309, issued to Jones et al. on Aug. 28, 1973.
Turning, for example in a lathe, advantageously is performed by traversing and removing material from the workpiece in both longitudinal directions. However, attempts to use the same insert within a holder for both grooving and turning, especially during turning in both directions, presents problems in securely and accurately maintaining the insert in position during these operations. In particular, during turning, and most especially upon the workpiece being traversed in the direction outwardly from that side of the holder to which the insert is clamped, the outward end of the insert held by a clamp to the toolholder tends to slip or rotate sideways due to the lateral force of the workpiece on the outward end of the insert. This is particularly the case where the bottom insert supporting surface of the holder is planar and perpendicular to the sides as in U.S. Pat. No. 3,754,309. Even where the bottom insert supporting surface of the holder is not planar, but is angled as in U.S. Pat. No. 6,000,885, issued to Erickson on Dec. 14, 1999, the insert tends to slip or rotate from the holder.
Attempts have been made to overcome the tendency of the insert to slip or rotate in the holder due to lateral force on the insert, for example by forming a diagonal notch in the insert and angling the clamp element to engage the notch and by forming recessed angled portions in the top and/or bottom surfaces of the insert, as in U.S. Pat. Nos. 3,754,309 and 6,000,885. However, such attempts have generally been imperfect to counter the force exerted on the insert as explained in U.S. Pat. No. 6,000,885. Furthermore, the attempts to date have not been applicable to small-size inserts. Small-size inserts are inserts having grooving widths in the range of from about 0.004 inch to about 0.150 inch and a body width of approximately 0.155 inch. Due to the small size of these inserts, it is impractical to attempt to form diagonal notches and recessed portions in the shank portion of the insert, particularly where the insert is formed of a material such as carbide or of hardened steel.
Thus, there exists a need for small-sized inserts which are adapted to resist forces exerted on the insert, particularly during turning.
It is an object of the present invention to provide a small-size insert which is securely held within a holder even when encountering lateral forces which tend to move the insert out of position with respect to the holder.
It is another object of the invention to provide a small-size insert which does not require recesses or notches in order to be securely held in position during grooving and turning.
It is still another object of this invention to provide a small size insert which can be securely held in position during grooving, cutting, as well as during turning in both directions along the workpiece.
These and other objects and advantages of the present invention will be apparent from the following description.
In accordance with the present invention an apparatus is provided which is adapted for use with a machine tool for grooving and turning. The apparatus comprises a body having first and second sides which are generally parallel and opposite each other, first and second ends, and top and bottom surfaces. The sides and top and bottom surfaces of the apparatus extend from adjacent the first end to the second end. Thus, the first end extends longitudinally beyond the sides and top and bottom surfaces of the body. The top surface has at least a portion thereof extending from adjacent the first end to the second end and is inclined downwardly from the perpendicular of the top end of the first side to the second side. The bottom surface has at least a portion thereof extending from at least adjacent the first end to the second end and is inclined upwardly from the perpendicular of the bottom edge of the first side to the second side. In the present invention, the first end may have generally parallel walls and may have a polygonal cross-section, and is adapted to be formed into an insert portion, for example by grinding into a desired shape of a cutting tool and/or grooving tool end. Alternatively, the first end may be a cutting tool and/or grooving tool end.
The apparatus of the present invention is intended to be utilized with a toolholder having a nest or pocket formed having an inclined bottom wall which is adapted to support the bottom surface of the apparatus of the invention. The apparatus of the present invention is intended to be securely retained in the nest or pocket of the toolholder by means of a lever-type clamp which is secured to the toolholder by means of a fastener, such as a machine screw, and exerts a downward force on the body of the apparatus. The clamp with which the apparatus of the present invention is held in the nest or pocket of the toolholder includes an inclined surface or angled end which cooperates with the inclined portion of the top surface of the apparatus to securely hold the apparatus in position in the toolholder.
Preferably, in the present invention, the top surface of the apparatus has a second portion extending from adjacent the first end to the second end of the apparatus perpendicularly from the top edge of the first side toward the second side. In such preferred arrangement, the inclined portion of the top surface may extend downwardly from the second portion to the second side at an acute angle with respect to second portion of the top surface. In this manner, the entire top surface need not be inclined, reducing the possibility that a burr or high spot on the nest or pocket bottom wall or on the apparatus body bottom surface may prevent the apparatus from firmly and securely being supported by the nest or pocket bottom wall.
Similarly, the bottom surface of the apparatus may have a second portion extending from adjacent the first end to the second end perpendicularly from the bottom edge of the first side toward the second side. In this preferred arrangement, the inclined portion of the bottom surface may extend upwardly from the second portion to the second side at an acute angle with respect to second portion of said bottom surface. As the lever-type clamp only contacts a portion of the top surface of the apparatus, only the corresponding portion of the top surface of the apparatus need be inclined. In this preferred arrangement, the apparatus of the present invention is securely held in position in the toolholder even upon encountering lateral forces during grooving, as heretofore explained.